The corrosion products which form on Cu rich amalgams will be identified by x-ray diffraction and scanning electron microscopy with energy dispersive x-ray analysis (SEM/EDX). Scanning Auger microscopy (SAM) and electron spectroscopy for chemical analysis (ESCA) will be used to aid in the identification by providing information on light element and valence state which are not available directly from the other methods. The formation of the corrosion products will be studied as a function of length of immersion in solutions. The microstructures of the corroded amalgams will be compared with those of non-corroded amalgams of similar age. The chemical compositions and lattice parameters of the phases in Cu rich amalgams will be more accurately determined and compared for 13 brands. They will also be compared with those of pure phases made in the laboratory. This information should lead to a rationale for differences in clinical performance of the various Cu-rich amalgam classes and brands. The weak corrosion prone gamma 2 (Sn8Hg) phase is greatly reduced or eliminated in most Cu rich systems. However, it is present to a greater extent in amalgams made from aged Cu rich alloys. Its presence and disappearance will be studied by x-ray diffraction for a variety of brands. Methods to induce artificial aging will be investigated, and the influence of aging on mechanical and electrochemical properties will be determined. A simple method which could overcome the aging problem by altering the conditions of alloy storage will be evaluated.